From 686f7b435d9974bfffa273168792ee0bb2ca1db8 Mon Sep 17 00:00:00 2001 From: Jeff Date: Tue, 17 Oct 2023 16:21:59 -0400 Subject: [PATCH] Write README and examples --- README.md | 59 ++++++++++++++++++++++++++++++++++++++++++++ examples/for_loop.ds | 8 +++--- 2 files changed, 64 insertions(+), 3 deletions(-) diff --git a/README.md b/README.md index 01aeaef..da330e0 100644 --- a/README.md +++ b/README.md @@ -118,6 +118,65 @@ reminder = { (output reminder.message) ``` +### Loops + +A **while** loop continues until a predicate is false. + +```dust +i = 0 +while i < 10 { + (output i) + i += 1 +} +``` + +A **for** loop operates on a list without mutating it or the items inside. It does not return a value. + +```dust +list = [ 1, 2, 3 ] + +for number in list { + number += 1 # This modifies x *only* in this block scope +} + +(output list) +# Output: [ 1 2 3 ] +# The original list is left unchanged. +``` + +To mutate the values in a list, use a **transform** loop, which returns a new modified list. + +```dust +list = transform number in [1 2 3] { + number - 1 +} + +(output list) +# Output: [ 0 1 2 ] +``` + +To filter out some of the values in a list, use a **filter** loop. + +```dust +list = filter number in [1 2 3] { + number >= 2 +} + +(output list) +# Output: [ 2 3 ] +``` + +A **find** loop will return a single value, the first item that satisfies the predicate. + +```dust +found = find number in [1 2 1] { + number != 1 +} + +(output found) +# Output: 2 +``` + ### Tables Tables are strict collections, each row must have a value for each column. If a value is "missing" it should be set to an appropriate value for that type. For example, a string can be empty and a number can be set to zero. Dust table declarations consist of a list of column names, which are identifiers enclosed in pointed braces. The column names are followed by a pair of curly braces filled with list values. Each list will become a row in the new table. diff --git a/examples/for_loop.ds b/examples/for_loop.ds index 453a296..3019d6b 100644 --- a/examples/for_loop.ds +++ b/examples/for_loop.ds @@ -1,6 +1,8 @@ -i = 0 -for i in [1 2 3] { +list = [1 2 3] + +for i in list { i += 1 (output i) } -(output i) + +(output list)